__ptrace_detach: avoid task_detached(), check do_notify_parent()
__ptrace_detach() relies on the current obscure behaviour of do_notify_parent(tsk) which changes tsk->exit_signal if this child should be silently reaped. That is why we check task_detached(), it is true if the task is sub-thread, or it is the group_leader but its exit_signal was changed by do_notify_parent(). This is confusing, change the code to rely on !thread_group_leader() or the value returned by do_notify_parent(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Tejun Heo <tj@kernel.org>
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1 changed files with 18 additions and 15 deletions
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@ -370,25 +370,28 @@ static int ignoring_children(struct sighand_struct *sigh)
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*/
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static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
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{
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bool dead;
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__ptrace_unlink(p);
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if (p->exit_state == EXIT_ZOMBIE) {
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if (!task_detached(p) && thread_group_empty(p)) {
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if (!same_thread_group(p->real_parent, tracer))
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do_notify_parent(p, p->exit_signal);
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else if (ignoring_children(tracer->sighand)) {
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__wake_up_parent(p, tracer);
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p->exit_signal = -1;
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}
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}
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if (task_detached(p)) {
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/* Mark it as in the process of being reaped. */
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p->exit_state = EXIT_DEAD;
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return true;
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if (p->exit_state != EXIT_ZOMBIE)
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return false;
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dead = !thread_group_leader(p);
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if (!dead && thread_group_empty(p)) {
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if (!same_thread_group(p->real_parent, tracer))
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dead = do_notify_parent(p, p->exit_signal);
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else if (ignoring_children(tracer->sighand)) {
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__wake_up_parent(p, tracer);
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p->exit_signal = -1;
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dead = true;
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}
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}
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return false;
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/* Mark it as in the process of being reaped. */
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if (dead)
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p->exit_state = EXIT_DEAD;
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return dead;
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}
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static int ptrace_detach(struct task_struct *child, unsigned int data)
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